Method of flanging tubular members



J. SQUIRES 1,966,053

METHOD OF FLANGING TUBULAR MEMBERS 7 Filed March 11. 1931 2 Sheets-Sheet l INVENTQR J'o 71 71 5 q u z I Qdwf ATTORNEYS- d 5 Z3 w L Patented July 10, 1934 1,966,053 Mrrrnon or FLANGING TUBULAR MEMBERS John Squires, Hagerstown, Md. Application March 11, 1931, Serial No. 521,796

8 Claims.

This invention relates to an improved method for forming a flange on the root end of a metal propeller blade.

Heretofore, in forming an external radial flange on the root end portion of a propeller blade of the type which is made from a tubular blank, it has been the practice to heat the root end portion of the blank to a workable plasticity, and to simultaneously upset the heated part to a desired thickness and force it into final shape in a single operation. lhe severe and abrupt deformation or the metal during this flange forming method breaks up its regular grain structure and produces a heterogeneous granular metal composition in the flange and in the metal at the junction of the flange and blade which is substentially weaker than the metal of the main portion or the blade.

The main objects of this invention are to provide an improved method for thickening the ek= trernity of the root end portion of a tubular propeller blade blank and forming it outwardly substantially normal to the longitudinal axis of the a blank so as to produce an external radial flange;

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to provide a method of this kind in which the end portion or" the blank is formed outwardly by a bending operation which preserves the regular grain structure of the metal and merely bends the lines of flow thereof without breaking them; to provide a bending operation of this character in which the force applied has a component exerted axially of the blank so as to thicken its end portion as the latter is bent outwardly; to provide a flange forming method in which the bending and upsetting of the metal is accomplished in succes sive steps by a series of dies, each of which is adapted to continue the bending andv upsetting actions where the preceding die left oil; and to provide a method of this character which obviates destruction of the grain structure of the metal at the extremity of a propeller blade blank in forming an end flange, and prevents weakening of the metal at the junction of the flange and blade.

Further objects of the invention are to provide an integral radial flange and adjacent thickened section on a tubular metal article in which the flow lines of the metal accurately conform with the curvature of the article, and to provide a flanged tubular article comprising metal having flow lines of concentric arcuate curvatures at the junction of the flange and tubular section of the article which terminate at the extremity of the flange and converge into substantially straight and parallel relationship in the tubular section.

An illustrative embodiment of my invention is shown in the accompanying drawings, in which:

Fig. 1 is a fragmentary vertical section of a pair of dies showing a propeller blade blank positioned with respect thereto for receiving the first operation of my improved flange forming method.

Fig. 2 is a view similar to Fig. 1, but showing the position of the dies and condition of the blank after the first operation.

Fig. 3 is a fragmentary vertical'section of the dies used in the second operation of the flange forming method showing a blank which has been subjected to the first operation, positioned between the dies ior receiving a succeeding operation.

Fig. 4 is a view similar to Fig. 3, but illustrati ing the position of the dies and the condition of the blank after the second die forming operation.

Fig. 5 is a fragmentary vertical section of the dies used in the third operation of my improved flange forming method showing a blank which has received the two preceding operations positioned therebetween.

Fig. 6 is a view similar to Fig. 5, but lllustrat ing the positions of the dies and condition of the blank after a final forming operation.

Fig. 7 is an enlarged reproduction of a microscopical photograph of an etched radial section of a flange formed in accordance with my improved method and showing the adjoining side portion of a propeller blade blank as it appears. prior to machining.

Fig. 8 is a view similar to Fig. 7, but showing a section of the root end portion of a propeller blade as it appears after machining.

Fig. 9 is an enlarged reproduction of a microscopical photograph of an etched section of a flange formed by a conventional upsetting operation and showing the adjoining side portion of a propeller blade.

In the form of my improved flange forming method, illustrated in the drawings, the root end portion 1 of a tubular propeller blade blank which has previously been heated to a workable plasticity, is inserted in a central passage 2 of a female die 3 with its end portion in registration with an enlarged end of the passage which is bounded by convexed walls 4. That portion of the passage which is immediately adjacent the enlarged end 4 thereof and in which the outer root end portions of the blank are received is tapered outwardly. The blank is held against'axial movement by supporting the opposite end thereof or by clamping the blank intermediate its end by apparatus (not shown) or in any suitable manner. Then a plunger or male die part 5 having a pilot portion 6 substantially equal in diameter to the inner diameter of the blank is inserted into the root end portion 1 thereof, as illustrated in Figure 1. The plunger 5 has an enlarged upper end adjacent which is located a tapering section having a concaved outer periphery '7.

As the plunger is inserted into the root end portion of the blank from the position shown in Figure 1 to that illustrated in Figure 2, the tapered section spreads or bells the metal at the extremity of the blank outwardly and during the movement of the plunger the tapered concaved periphery 7 of the latter bears axially upon the walls of the blank. Since the tapered periphery 7 of the plunger is inclined with respect to the part in which the plunger moves, the force exerted upon the inner periphery of the blank may be considered as two \components, one, illustrated by the arrow 8 in Figure 2 and the other illustrated by the arrow 9. In the first step of the method illustrated in Figures 1 and 2, the axially component 8 of the force is somewhat larger in magnitude than the radial component 9. These two components simultaneously upset the extreme end portion of the blank so as to increase the thickness of its walls and bend the thickened wall portions outwardly. The outwardly tapered portion in which the adjacent side parts of the blank are received permits the walls of such parts to expand under the axial component 8 for producing the tapered wall section shown in Figure 2.

The blank is then removed from the female die 3 and placed in a female die 10, shown in Figs. 3 and 4, for receiving the next successive step of the flange forming operation. The female die 10 has a central passage 11 which is provided with an enlarged extremity 12 for receiving the belled and thickened end portion of the blank. Formed at the junction of the central passage 11 and the enlarged end portion 12 thereof, is a convexed shoulder 13 which. differs in curvature from that of the convexed shoulder 4 of the die 3 and which more closely approaches a normal relationship to the axis of the passage 11 than the relationship of the convexed walls 4, shown in Figs. 1 and 2, to the axis of the passage 2.

A plunger 14 having a pilot portion 15 which closely fits into the interior of the tube is then forced inwardly from the position shown in Fig. 3 to the position shown in Fig. 4. Located at the junction of the pilot portion 15 and the main part of the plunger is a tapered section 16 which has a concaved periphery 16' of greater radius of curvature than that of the concaved periphery 'I of the plunger 5. As the concaved periphery 16' bears upon the previously belled and thickened end portion 1 of the blank, it exerts a force having an axial component and a radial component, of substantially equal magnitude indicated by the arrows 17 and 18, respectively, in Fig. 4. The force components 17 and 18 further upset the metal of the heated end portion 1 of the blank and bend the same further outwardly thereby increasing the thickness of the walls of the blank at its root end portion and bending them closer to a normal relationship to the axis of the blank.

After the root end portion 1 of the blank has been formed between the die 10 and plunger 14 to the condition shown in Fig. 4, the blank is removed from the die 10 and inserted into a central passage 19 of a female die part 20 with the thickened and belled portion located in an enlarged end 21 of the central passage. Extending radially from the central passage 19 of the female of the blank at which the flange 2'7 is formed,

die 20 is a face or shoulder 22 which is located at the inner extremity of the enlarged part 21 of the passage. A male dieor plunger 23 having a pilot portion 24 which is receivable in the interior of the blank and a cylindrical part 25 which fits into the enlarged end portion 21 is then forced upon the belled and thickened end portion in the manner shown in Figs. 5 and 6. The cylindrical part 25 of the plunger has a face 26 which is substantially normal to the face 22 of the female die 20. As the dies 20 and 23 come together the thickened and belled part of the blank is compressed into a radial flange 27 having uniform thickness substantially greater than that of the walls of the blank.

The peripheries of the central passages 2, 11 and 19, are flared outwardly somewhat adjacent their respective enlarged end portions so as to permit crowding of the metal adjacent that part under the action of the axial components of the forces applied during belling of the extremity of the blank. This construction of the dies causes that portion of the blank immediately adjacent the flange 27 to be thickened, as illustrated in Fi 6.

The advantage of simultaneously belling and upsetting that portion of the blank at which the flange is formed may be clearly seen by comparing the grain structure and flow lines of the metal shown in the reproductions of microscopical photographs of etched sections of propeller blades, one having a flange formed thereon by the above method and the other having a flange formed by a conventional mashing operation. The flow lines appearing in the section of the blade, shown in Figs. 7 and 8, which has a flange formed in accordance with my improved method, are bent but they are continuous and unbroken and the grain structure of the metal in the flange 27 is substantially the same as that in the main portion of the blank.

The internal structural characteristics of the metal are preserved by avoiding endwise mashing of the metal at the extremity of the blank and substituting for the latter gradual bending of the end portion of the blank by separate successive operations in which the bending is accompanied by simultaneous upsetting of the metal to increase the thickness of the walls of 5 the blank as they are belled or bent outwardly.

The flow lines extend continuously from the outer edge of the flange through the junction of the flange and the adjacent side part of the tube and into the tube proper without interruption. 130 At the junction of the flange and the side of the tube, the flow lines follow concentric curvatures and they converge in the thickened wall of the root end portion to substantially straight parallel relationship. When the outer periphery of the root end portion is machined, as illustrated in Fig. 8, the flow lines terminate at successive locations on the outer periphery of the blade.

When a flange. is formed by single mashing operation the flow lines in the flange and in a substantial length of the adjacent portion of the walls of the blank are broken and distorted producing a heterogeneous structure of the type illustrated in Fig. 9 which is weak and undesirable in propeller blades. The lines of flow in the metal of a mashed flange extend substantially parallel to the length of the blade forming a weak section in the interior of the flange at which fail- .1 has been found to occur. When the end por- 150 tion of the flangeis bent outwardly by my improved method, the flow lines in the metal thereof extend transversely of the length of the blank, as shown in Fig. 7 forming a strong section for resisting fracture by the tremendous centrifugal forces which are exerted on the flange when a blade is held against outward movement from a propeller hub by the flange.

Although but one specific embodiment of this invention has been herein shown and described, it will heunderstoodithat numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims. I

I claim: t

1. In manufacturing a propeller blade from a tubular blank, the method of forming a flange on one extremity of said blank which consists in heating said blank to a workable plasticity, initially bearing simultaneously upon the interior of substantially all portions of said heated end portion with a force having a component directed axially of said blank for increasing the wall thickness thereof and having'a simultaneously effective component directed outwardly for belling the heated end of said blank, bending the thickened and belied end of said blankinto a plane substantially normal to the axis thereof, and compressing said end of said blank to a substantially uniform thickness between dies having faces substantially normal to the axis of the blank.

2. In manufacturing a propeller blade from a tubular metal blank, the method of forming a thickened radial flange on an endthereof which consists in heating an end portion of said blank, simultaneously spreading substantially all portions of said heated end portion outwardly to an increased inner diameter and simultaneously crowding the metal thereof, and simultaneously bending the outwardly spread end portion of said another pair of dies having registering concaved and convexed faces respectively of a different curvature, and compressing said belied end portion between dies having faces normal to the axis of said blank. I l

4. The method of forming a flange on an extremity of a tubular metal propeller blade blank which consists in heating anend portion of said blank to a workable plasticity, simultaneously belling said heated end portion and crowding the metal of the same between different pairs of dies of which one'die of each successive pair has a section of said blank with successive forces having gradually decreasing components directed axially with respect to the axis of said blank and simultaneously effective gradually increasing components directed radially with respect to said blank, and finally bearing upon said heated end portion with an axially directed force only. t.

6. The method of forming a flange on an extremity of a tubular metal propeller blade blank which consists in simultaneously bending substantially all portions of the walls of an end portion of said blank outwardly and simultaneously crowding the metal of the same to an increased thickness in successive die forming operations of increasing bending magnitude and decreasing crowding force so as to obviate interruption of the continuity of the flow lines in the grain structure of the metal of said blank, and shaping said end portion between dies having opposed faces, each normal to the axis of said tube.

7. In manufacturing a propeller blade from a tubular metal blank, the method of forming the root end portion thereof which consists in heating one end section of said blank, simultaneously spreading substantially all portions of the extremity of said heated end portion including its inner periphery outwardly and simultaneously crowding the metal of substantially all portions of said end section, and the metal of the adjacent tubular side portion so as to thicken said extremity and form tapered wall sections at the adjacent side part of said root end portion, and bending the outwardly 116 spread thickened extremity into a desired relation to the axis of said blank and compressing said extremity to a desired thickness between dies having faces disposed at desired relations to the axis of said tube.

8. The method of forming a flange on an extremity of a tubular metal propeller blade blank which consists in heating an end portion of said blank to a workable plasticity, simultaneously belling said heated end portion and crowding the 125 metal of the same under the influence of simultaneously effective components of force directed radially outwardly on said heated end portion and axially on the extremity thereof respectively, simultaneously belling and crowding the metal 33 of said heated end portion further under the influence of a simultaneously efiective radially outwardly directed component of larger amplitude than the first corresponding componentand an axially directed component of lower amplitude than the first corresponding component and compressing said belled end portion between dies having faces disposed at a selected angle to theaxis of said blank.

JOHN SQUIRES. 

